<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="../jQuery/js/jquery-1.12.4.min.js"></script>
    <script>
        $(function(){
            var $h3=$('#h3')
            $h3.prev().css({background:'red'})
            $h3.prev().prop({'value':'点你'})
            //html为标签包裹的内容
            $h3.html("<span style='{color:'red'}'>哈哈哈</span>")
            // append为添加
            $h3.append("123")
            alert(p.length)
            alert(p.name)
        })
    </script>
</head>
<body>
    <div>
        <p name='pp'>haha</p>
        <input type="button" value="点我">
        <h3 id='h3'>三级标题</h3>
    </div>
</body>
</html>